Step 1
Use the tweezers to pull out a segment of DNA from the hepatitis B virus.

A subunit vaccine makes use of just a small portion of a pathogen. For a virus,
the vaccine can contain just a piece of the protein coat that surrounds the
virus's DNA (or RNA). Even small portion of a virus is sometimes enough to
stimulate an immune response in the body.

There are several ways to produce a vaccine for hepatitis B vaccine. For your
vaccine, you'll use genetic engineering techniques.

Step 2
Add the segment of DNA to the DNA of a yeast cell (which is in the yeast
culture).

A segment of the virus's DNA is responsible for the production of the virus's
protein coat. You will add this segment to the DNA within a yeast cell.

The yeast cell, as it grows, will "read" the viral DNA incorporated in its own
DNA and produce the protein that makes up the protein coat of hepatitis B.

Step 3
Use the purifier to isolate the hepatitis B antigen produced by the yeast cells.

The vaccine, once administered, will stimulate the immune system to attack the
antigen (i.e., the protein coat). Then, if the inoculated person is later
exposed to the virus, the immune system will quickly respond to the invader and
eliminate it before it has a chance to spread widely.

To finish making the vaccine, you need to separate the proteins from the yeast
cells.

Step 4
Fill the syringe with the purified hepatitis B antigen.

The isolated hepatitis B protein, produced by the yeast cells, contains none of
the viral DNA that makes hepatitis B harmful. Therefore, there is no
possibility of it causing the disease.

Done
The hepatitis B vaccine is complete.

Select another pathogen.

Congratulations. You have produced a subunit vaccine for hepatitis B.

Another example in the subunit category is the anthrax vaccine approved in the
U.S. (The countries of the former Soviet Union have an attenuated version of
the vaccine.) The U.S. vaccine is currently administered to military personnel.